"It took us a while and a bit of a headache to discover why the radiator was hot and cold when the heating was on, we got to think there was a problem in the system so we emptied it and refilled it a few times; after a lot of searching online and with the "problem" still going on, we found out that this type of TRV switches off automatically once the right temperature has been reached, which it is a positive thing but it was not clearly explained on the Screwfix website or on the item instructions either. Otherwise it is working perfectly so far."